Archive for February, 2010

Looking Ahead to Forties!!!
February 28, 2010

I hope everyone had a wonderful weekend. February comes to an end in an appropriate manner. I say that because it has been a cloudy month with no real cold and no real warmth. The coldest temperature in February was 11 degrees on the 12th. The warmest was 38 degrees on the 18th and 19th. Usually we would get at least one or two days in the 40s and we normally would have a few days with below zero temperatures. Milwaukee has not had a single below zero temperature all winter. It becomes very unlikely to go below zero in March.

Now, it is time to look ahead. The first couple of days this week will be cool with highs in the 30s, but as the week goes on the highs will make it to the 40s. This is the first time we will have temps in the 40s since January 24th when it was 43 degrees.

The above image is the GFS model depicting surface temperatures well into the 40s for all of Southeast Wisconsin. The warm air will be drawn north due to a strong low pressure center developing in the Great Plains.

The aforementioned storm is going to be a very wet one for us. The key to what type of precipitation we will get from this strong storm will be the track of the low. At this point, it looks like the low will go to the west and north of our area. That means warm air keeps the majority of the precipitation as rain and not snow. If this storm moves in as expected we could get an inch of rain. This will go a long way to melting a lot of snow, but we will have to watch closely for the potential of flooding. Stay with weather watch 12 for the latest. Thanks for reading.

Mark

Chile Earthquake & Tsunamis – Plus 40s Ahead
February 27, 2010

***Watch WISN 12 News for the latest forecast information!***

Thank you for spending part of your weekend with us on the Weather Watch 12 blog!  Remember…you can still view the long range March forecast…just check the blog entry right below this one.

Once again a very strong earthquake struck, this time in the Country of Chile.  The earthquake had a magnitude of 8.8 on the Richter Sclale.  Believe it or not this earthquake was one of the strongest ever recorded in the world, and 500 times stronger than the Haiti quake!  The Chile earthquake formed on the ‘Pacific Ring of Fire’ along the Peru-Chile Trench.  Below is a look at the entire Ring of Fire…all of these fault lines can cause significant earthquakes.

The big concern right after the earthquake was the potential for a devastating tsunami across the Pacific…including in Hawaii.  A Tsunami Warning was issued 10+ hours in advance.  It turns out and thankfully so, the Tsunami only created slightly higher water levels around the island chain when it passed by.

Since we have now had 2 very large earthquakes occur in the past two months, let’s take a look at how a Tsunami forms.  The image below shows the center of an earthquake labeled by the red circles.  The shifting of the earth caused a push up and down in the water…creating an upward wave.  This is the start of a Tsunami.

A more detailed explanation is below including 3 images to highlight what happens after the Tsunami forms.

A) An earthquake results from plate shifting at a subduction zone (oceanic plate being subducted under continental plate). Displaced water forms a tsunami. B) Tsunami separates into two distinct waves – local (to right) and distant (to deep water). C) As local wave encounters continental slope, it gains amplitude (height) and slows down. The trough of the wave, if it encounters the coast first, will cause a drop in water level (drawdown). Note the distant wave traveled much farther from the point of origin since it is moving faster in deep water (adapted from USGS). Note: Wave heights and slopes are exaggerated in comparison to water depths.

If you have questions about the earthquake information or Tsunamis please let us know by leaving your question in the comments section of the blog.

Overall our weather looks very quiet heading into the start of March.  The models have been underdoing temperatures to the tune of about 2-4 degrees each day for Milwaukee.  To me that means we should be in the mid 30s to low 40s over the next week.  The 40s will probably hold off until Thursday at the earliest.  It is safe to say that our snowpack will take a hit over the next week.

Make sure to check back to the blog on Sunday, Mark will have an update on the weather conditions we are expecting and possibly touch on the wet storm that looms for the 7-9 timeframe.  If you are wondering…this is a storm that was highlighted in the long range March forecast in the blog entry below.  Check it out!

Have a great weekend!

Jeremy Nelson

March Forecast
February 26, 2010

***Watch WISN 12 News for the latest forecast updates!***

The days are growing longer, the average high temperature continues to climb, one thing is certain…Spring is near! The most asked question to anyone on the Weather Watch 12 team right now is, “Is Spring almost here?” The easy answer is yes, Spring officially begins on March 20. The tough question is when will the weather finally feel like Spring?

In today’s blog we will go over the March forecast and look at some of the highlights that I forsee for the month, and also the general temperature and precipitation trends.

Let’s start by looking at the hard numbers for an average March in Milwaukee.

  • March 1 Average high: 37 low: 23
  • March 31 Average high: 48 low: 32
  • Average March Snowfall: 7.4″
  • Average Precipitation: 2.59″

If you are new to the blog then you missed the long range forecasts that I made for January and February. The forecast made in advance of both of these months was overall very good. Here is a quick piece of the February forecast that was posted in the blog on January 26.

February 8-14

For this forecast I do think a storm will form over the Midwest in the Feb. 7-9 timeframe and likely bring snow to many areas. If enough warm air is pulled in, a mix or rain could occur. This will be one of potentially two major storms we see during February, and could be the biggest snow maker of the month for parts of our area. This potentially large storm could impact the region through the 10-11 as a quick shot of arctic air is drawn in on the backside of the storm.

This was the biggest success of the February forecast calling for likely the biggest snow for the month to occur with this storm and on the exact dates. Milwaukee’s snow total from this storm was 8.8″…easily the biggest of the month. So what are my long range forecasts based on? A weather pattern theory called the LRC.

Making long range forecasts is always tricky and never perfect, but a weather pattern theory known as the LRC allows for accurate long range weather forecasts to be made. LRC stands for Lezak’s Recurring Cycle.

I have been very excited to introduce this theory to viewers here in Southeast Wisconsin. I first learned about the theory 4 years ago while working in Kansas City. Here is what the theory states:

  • A unique weather pattern sets up every year between October 1st and November 10th
  • The weather pattern cycles, repeats, and continues through winter, spring and into summer. Identifying the cycle length helps tremendously when making long range weather predictions.
  • Long term long-wave troughs and ridges become established and also repeat at regular times within the cycle. These dominant repeating features are a clue to where storm systems will reach peak strength, and where they will be their weakest.
  • The LRC is a winter-long pattern! There is a pattern! It isn’t just one long-wave trough, storm system, or ridge. It is a sequence of troughs and ridges that are cycling across the Northern Hemisphere.

To put this in very simple terms, the weather pattern that occurs in October and November repeats thru the Winter, Spring, and into the Summer. The cycle length will vary each year. Determining the cycle length each Fall really holds the key in using the LRC to forecast into the future. A very good idea of the cycle length is usually determined anywhere from late November thru December. Once the pattern goes thru its second cycle a period of days can be placed on the cycle length. As I have mentioned in previous blog entries, the cycle length this year is about 60-62 days.

This brings us to the what lies ahead for the month of March. For this forecast I will breakdown the month into two halves highlighting trends in temperatures and precipitation. Also, give the timing of possible storms during the month.

Let’s start by looking back to the month of January, since this month’s overall pattern should match up closely with what we see in March. During the month there was really only one big storm for Southeast Wisconsin. This occurred on January 7-8 when what I’ll call a ‘hybrid clipper’ dove into the Midwest. This storm had a long duration of northeast winds…so what would have been a 2″-3″ snow, quickly turned into a snow of over 7″.

Below is the 500mb archived map of what this level of the atmosphere looked like that day. Notice the big upper level low over Iowa. The question is now how will this part of the pattern look when it comes back in March?

March 1-15

The month should get off to a cool start with high temperatures generally between 30-35 degrees for the first several days. Depending on nighttime lows the first few days may be a little bit below average temperature-wise. Closer to the end of the first week highs may be around 40.

The biggest storms during the first week of March should stay closer to the Gulf Coast and also the East Coast.  Another decent snow is possible for parts of the mid-Atlantic or Northeast in the first week.  For Southeast Wisconsin the most active part of the first half of March should occur between March 7-12. If we are going to see a snow of 3″ or more or see some rain/sleet around it would be in this time window. Remember…we are on roughly a 60-62 day cycle and the upper low from around January 7-8 should repeat in some fashion during the second week of March.

Once we get toward March 13-15 I believe a drier and slightly warmer part of the pattern will begin.  The first half of the month will likely see average or slightly below average temperatures.

March 16-31

Back in November and again in January around the 17-19 there was a storm that stayed south of Wisconsin and hit areas from the Tennessee Valley to the Gulf Coast to the East Coast. Another potentially wet storm should stay south of Wisconsin and pay a visit to some of these same areas that have had a very wet winter. Around Southeast Wisconsin the early part of this period should bring fairly quiet weather, with mainly above average temperatures. This means highs should be in the upper 30s to 40s.

March will likely come in like a lamb…but could it exit like a lion? Let’s look back to late January to help us answer this question. Below is the 500mb archived map from January 25. This shows a very large upper low over the Midwest and western Great Lakes. This storm produced 0.26″ of precipitation in Milwaukee…but 60-62 days prior to January 25…this storm produced over 1.30″ of rain in November!

The previous two times through the cycle this part of the pattern has produced precipitation in Southeast Wisconsin. I believe that a potential ‘bigger’ storm will impact the region around March 26-30. By this time the average high is in the upper 40s…so rain, a mix, or snow could all be associated with this storm. The month will then end with below average temperatures.

Overall, the most exciting weather once again this month will likely reside from the South to the Southeast and then into the East.

Please keep in mind as we get closer to Spring the jet stream…which helps to guide systems across the country and also separates warm and cold air will slowly begin its seasonal shift to the north. This will play a role in where this potential storm(s) travels, but overall the same general weather pattern will be repeating. With the jet stream lifting north and warmer air progressing northward, March will likely mean the nation’s first taste of severe weather this year!

For the month of March in Milwaukee I think temperatures will end up above average and precipitation near or below average. Barring any big lake effect snows, snowfall should be around average. There may be one major storm during the month…likely in one of the periods highlighted above.

Thank you for reading and make sure to post your questions and thoughts to our comments section of the blog!

Jeremy Nelson

Snow Pictures & Not Our Average Lake Effect Snow
February 25, 2010

***Watch WISN 12 News at 5, 6, & 10pm for the most up-to-date forecast!***

Thank you for taking a few minutes to read the Weather Watch 12 blog! The past 24 hours provided many twists and turns in our weather. The end result was heavy bands of lake effect snow in fairly isolated locations. Much of Milwaukee County picked up 2″-5″ of snow in a very short period of time. In this blog we will take a look a couple of pictures from the peak of snow…and also look at why the snow wasn’t our average lake effect event.

On Wednesday I spent the 5 & 6pm newscasts at Klode Park in Whitefish Bay…right next to our snow engine…Lake Michigan. When I arrived a snow loving group of kids had just finished sledding. Here is a picture of Jonah & Hayden Nelson, Belle Patzer, & Henry Davis.

The powdery snow totaled about 4.5″ in Whitefish Bay. Most of the snow there had ended by 6pm.

In order for lake effect snow to occur we need cold air to flow over the warmer lake waters and the wind to blow off from Lake Michigan…meaning some sort of a northeast wind. Typically we look for this northeast wind at the surface. But really anywhere from the surface to about 1500 meters or about 5000 feet above the ground the wind can greatly influence or create lake effect snow.

Around 4pm on Wednesday…I arrived at Klode Park in Whitefish Bay and took this picture. The flag shown below was indicating a northwest wind. That means not a favorable wind for lake effect snow, but yet there was moderate snow falling.

The surface map from late Wednesday afternoon also showed the northwest surface winds in Milwaukee and Racine…but yet lake effect snow was occurring. Below is the surface map, Milwaukee is labeled ‘MKE’. The black line attached to the pink colored in circle by Milwaukee is the wind barb. The wind barb shows the direction and wind speed.

So if the winds in Milwaukee were out of the northwest for most of Wednesday afternoon…what was the driver of our lake effect snow? That question can be answered by looking at what is known as a sounding. Each day in select cities the National Weather Service launches a weather ballon that has instruments attached to it to measure temperature, dew point, wind speed and direction, etc. This data is then translated into upper air charts. The closest city to Milwaukee that launches a weather balloon twice a day is Green Bay.

The map that was created on Wednesday that incorporated the sounding data from across the United States holds the key to why our lake effect snow occurred in Milwaukee with a northwest surface wind.

Below is the 925mb map. If you are wondering 925mb is roughly 750 meters or 2500 feet above the ground. This map shows a due northeast wind in Green Bay at this level. The blue line with two barbs indicates a northeast wind of 20 knots or about 23 mph. This northeast wind persisted from the northern part of Lake Michigan all the way to Milwaukee.

The end result was lake effect snow bands which moved from the north-central part of Lake Michigan all the way to Milwaukee. The bands picked up lots of moisture and dumped that as a quick burst of heavy snow in Milwaukee. This isn’t the first time, and it won’t be the last that lake effect snow produces more snow than the forecast calls for. But hopefully this blog entry will help you understand why this type of forecast is very difficult to detect BEFORE the heavy snow occurs.

If you have questions or thoughts please post them to the comments section of this blog. Make sure to check out the blog on Friday…we will be issuing our long range forecast for the month of March!

Have a great day!

Jeremy Nelson

Lake-effect surprise
February 24, 2010

Good evening, everyone. Many of you are probably just getting back in from shovelling the lake-effect snow. Last night, I had a forecast of .5″-1.5″ of snow for today. Clearly, I missed something. That something was the amount and intensity of lake-effect snow. Even though the winds throughout the day at the surface were northwest. Just above the surface the winds were northeast. This is difficult to pick up on in forecasting and I clearly missed it last night. Until today’s forecast, I had felt pretty good about our overall winter forecasting this season. Mother nature has a way of keeping you humble.

Here are some of the latest snow totals:

Downtown Milwaukee: 5″

West Allis: 4.6″

Whitefish Bay: 4.5″

Shorewood: 4.5″

Mitchell International: 2.4″

Franksville: 2.5″

Cambellsport: 3″

Lomira: 3.4″

If you have any other totals send them our way.

The snow is not quite done yet in Racine and Kenosha counties. They may pick up another 1″ in the next hour or two before the snow tapers off by 10pm. Thanks for reading.

Mark

Heavy Lake Effect Snow Bands
February 24, 2010

***Watch WISN 12 News today at 5, 6, & 10pm for the latest on the lake effect snow!***

Just a quick update on the heavy lake effect snow bands that are affecting parts of Southeast Wisconsin.  A Lake Effect Snow Advisory is in effect until Midnight for Milwaukee County and 3am for Racine and Kenosha Counties.  One quick burst of snow just moved by our station at 19th and Wells and produced 1″-2″ of snow.  More heavy lake effect snow bands will rotate inland from late afternoon into the evening.  Snow totals in isolated spots will total 4″-5″, but overall many areas will be in the 1″-3″ range.

Below is a radar image from around 3pm.  This shows a very intense lake effect band about to move inland.  This will produce snowfall rate of 1″ to possibly 3″ per hour!

Lake effect snow by nature generally occurs in narrow bands…so while some areas may pick up a quick 3″-5″ of snow…a few miles away may only see 1″-2″.  Please use caution traveling this evening as roadways will become snow covered and visibilities will be reduced as wind will gust above 20mph.

If you have snow totals to pass along please post them to the comments section of the blog.  For more information on the snow today please read the blog entry from this morning that was talking about the snow for today.

Look for more weather updates on our Facebook Page  WeatherWatch 12

Jeremy Nelson

Quick Bursts of Snow
February 24, 2010

***Watch WISN 12 News at 5, 6, & 10pm for the latest on the snow and cold!***

Thank you for stopping by the Weather Watch 12 blog. As expected, areas of snow are working their way through Southeast Wisconsin today. Some of the snow showers developed as lake effect snow bands and have pushed inland. These snow bands are the most intense and could provide a very quick half inch to maybe 2-3 inches or more of snow. Visibilities will also be reduced for a time in these intense snow showers.

If you would like to track the snow right down to where you live make sure to check out our interactive radar at

www.wisn.com/irad


Snow totals from the narrow heavy bands of snow as of Noon included:

  • Lomira/Brownsville 3.4″
  • Campbellsport 3.0″
  • Fond du Lac 2.0″-3.0″
  • Milwaukee dusting of snow

Please post your snow totals to the comments section of the blog. We will share them on WISN 12 News! Let’s take a look at a couple of radar images and look ahead to the rest of today. The first radar image was from around 9:30am from the Milwaukee/Sullivan radar. The city of Milwaukee is labeled with a ‘*’. One band of moderate to at times heavy snow was located from east-central Fond du Lac county south through extreme western Washington county. This snow band could drop a quick half inch to one inch of snow. It was drifting to the south-southwest. As it moves farther inland it will continue to weaken.

As our Alberta Clipper continues to push by the wind direction will play a huge role in a heavy band of lake effect snow and where it moves. Below is the Green Bay radar from around 9:30am. The city of Green Bay is highlighted by a ‘*’. This image shows the same band of snow extending into Fond du Lac county, but really of note is the HEAVY snow over the northwest part of Lake Michigan. This band will continue to push southwest. The big question is will it reach Southeast Wisconsin?

To answer that question we need to take a look at the winds. Remember…for Milwaukee to get lake effect snow bands the wind must be northeast or north-northeast. As this weak Clipper moves by today the wind will turn to the northwest. This is already beginning to happen. So this heavy snow band will have a race against the shifting winds to see if it can reach areas from Sheboygan to Milwaukee or Racine.

Here is the surface map, notice the winds are northeast on the EAST side of Lake Michigan, but in Milwaukee the wind is north-northwest. If you are wondering Milwaukee is the city identified by ‘MKE’.

I think most of Southeast Wisconsin will see snow showers today, some of those bands will contain a period of moderate to heavy snow. Areas that get under the heavy snow could pick up a quick 2-3″+ of snow. While areas that are just grazed or see a weak snow shower will only pick up a dusting to half inch. Use caution traveling around the area today because visibility may be just fine, and then is quickly reduced as you enter a burst of snow.

For more updates today check out WeatherWatch 12 on Facebook at WeatherWatch 12 More updates are also available on Twitter!

Again, our interactive radar is the best way to track the bands of snow today. This is a neat feature and it is free!

www.wisn.com/irad

Have a great day!

Jeremy Nelson

More Light Snow…A Shot of Cold
February 23, 2010

***Watch WISN 12 News at 5, 6, & 10pm for the latest forecast updates!***

Thank you for stopping by the Weather Watch 12 blog! Over the next few days you may catch yourself asking…is winter ever going to end? That is because skies will be cloudy, temperatures will be below average and there will be on and off light snow for the next couple of days.

If you are looking forward to warmer days and the start of Spring I do have some good news. I will be posting the long range forecast for the month of March exclusively in the blog either tomorrow or Thursday. Remember, the long range forecasts which have worked out very well so far this winter are based on the LRC.

Let’s take a look at the next couple of days and put some numbers on the snow we are expecting. An Alberta Clipper will dive into the Great Lakes over the next 24 hours. This will provide just enough lift to the moisture we have around to translate into areas of light snow. Below is a surface map for tonight into early Wednesday. Notice Milwaukee is in the outlined area of light snow. Sitting back in the upper Midwest is an arctic high…this will keep temperatures below average for much of this week.

If we see accumulating snow across southern Wisconsin I think most of that would be tonight into Wednesday. Before we get there, quick bursts of snow are possible today as snow showers pass through Southeast Wisconsin. Since temperatures are in the low 30s I don’t think any of this would stick on the main roads today.

For tonight thru Wednesday an area of light snow will move across Southeast Wisconsin. One thing we will have to watch closely as the clipper moves by is IF and for HOW LONG the winds may turn off the lake. If the winds become northeast and cold air spills over the lake a period of lake effect snow will be possible. This would add to the snow totals along the lakeshore locations.

Remember back to last Friday and Saturday when I posted the RPM forecast for the snow this past Sunday Night and into Monday…the RPM really nailed the forecast with the low snow totals.

Now this time around…the RPM is picking up on a brief period of lake effect, where other models are turning the winds to the north-northwest quicker. This means the RPM is forecasting totals a little higher over the next couple of days. Nothing major, but 1-2″ are possible with this forecast. Below is the RPM forecast, with Milwaukee marked with a ‘*’.

It is safe to say that most areas will see anywhere from a half inch(heavy dusting) to around maybe 2 inches of snow over the next couple of days. We’ll watch the forecast closely…because if the winds are off the lake for a longer or shorter period of time…the forecast will be tweaked. If and when it does snow again, please post your snow totals to the comments section of the blog and we will use them on WISN 12 News.

As the low moves by winds will increase and pull in colder air. Winds will increase to 15-25mph on Wednesday. It will certainly feel like winter with high back in the 20s…10 degrees below average. Nighttime lows will fall to the teens, with inland areas possibly in the upper single digits.

Below is the NAM temperature forecast for Thursday afternoon. Notice the highs in southwest Minnesota of only 5 to 10 degrees above zero…at least Southeast Wisconsin will have highs in the 20s.

That is the latest on the setup for the next several days. Make sure to wactch WISN 12 News for the most up-to-date forecast. Also, please join our Facebook fan page at WeatherWatch 12 We also send out Twitter updates several times a day!

If you have weather question, just post it to the comments section of this entry! Have a great day!

Jeremy Nelson

Snow Totals…Not Very Impressive
February 22, 2010

The snow totals are in from our little storm last night. The heaviest snow stayed to our south and this storm moved very quickly. The accumulating snow fell from about 10PM Sunday night to 7AM Monday morning. You may have heard some wild totals that were forecasted for this storm, but you did not see any of that here.

The above map is the totals from trained weather spotters around SE Wisconsin. Officially here are some of the totals:

MILWAUKEE: 2″

RANDOM LAKE: 2.5″

PLYMOUTH: 1.9″

MEQUON: 2.2″

MUKWONAGO: 1.8″

RACINE: 2.1″

CALEDONIA: 2.5″

WATERTOWN: 1.5″

OCONOMOWOC: 1.5″

JACKSON: 1.5″

Cooler temperatures are set to arrive on Tuesday and with the cooler temps will come some snow showers starting Tuesday afternoon into Wednesday morning. This could add up to an inch after is all is said and done, but the bigger story will be the chilly temps. Highs will only be in the middle 20s on Wednesday and Thursday. This is 10 degrees cooler than average. Our average high is now up to 35 degrees.

The above image is our in-house computer model showing the snow totals of around one inch for the snow showers on Tuesday afternoon and Tuesday night.

It has been a strange winter in that after December 1st when we hit a high of 51 degrees, the warmest temperature has been 43 degrees on January 24th. The coldest temperature so far this winter in Milwaukee has been one degree on December 10th. On average in Milwaukee, we usually get 10 days below zero each winter. That will clearly not happen this winter.

Thanks for reading the blog and have a great day. Enjoy the pretty snow that was wet enough to stick to everything.

Mark

Unimpressive Storm
February 21, 2010

UPDATE AT 10:35 PM. SNOW TOTALS STILL LOOKING AROUND 2″-4″ FOR MOST OF AREA. SNOW IS FALLING ALMOST EVERYWHERE IN THE AREA. STORM IS MOVING QUICKLY AND THE SNOW WILL TAPER TO FLURRIES BY MID-MORNING. HERE IS THE LATEST IN-HOUSE MODEL. IT STILL BRINGS MOST AREAS 2″-4″.

There is always a danger in putting snow forecast totals out too early on storms because it really is not until the last 12 hours or so that you have a really good handle on how much snow is really going to fall. We have been watching this storm at weather watch 12 for the better part of a week. The storm track now looks to take it a little farther south and that means we are on the northern fringe of the storm. On top of that, the low pressure center is not very strong to begin with. We are still going to get snow, but not very much. The greatest totals will be near the border of Illinois where a few amounts may touch 5″, but most areas of Racine, Kenosha, and Walworth counties will get between 2″-4″. Milwaukee and Waukesha will get around 2″-3″. North of Milwaukee will get around 1″-2″. Certainly not a big storm by our standards. As usual, be ready for a slow commute on Monday morning with snow falling as you head off to work and school.

I want to show you the latest computer model trends on this storm:

The above image is our in-house RPM model. Every run it has diminished the amount of snow. It is maxing snow totals to 2″ in extreme SE Wisconsin. I think this is underplaying it a little, but it does go to show that this storm is not living up to what it once looked like it was going to be.

The noon run of the NAM model only pushes out .3″ of liquid for Milwaukee with a little more near the Illinois border. The temperatures as the snow falls will be just under freezing so the ratio will be around 10:1. This would max Milwaukee out around 3″.

The 6AM run of the GFS model is the last one available right now. It is very similar to the NAM bringing the highest totals south of Wisconsin. Northern Illinois will pick up as much as 6″ of snow, but the track is far enough south to keep us in the lighter snows.

As always, count on weather watch 12 to keep you updated on this storm and you can follow it on Interactive Radar as well. Thanks for reading and drive safely as the light snow moves in.

Mark